The objective of this proposal is to investigate new methodologies for the early detection and identification of reading disabled children. Current approaches to the identification of reading disabilities suffer from statistical and theoretical shortcomings which result in high rates of misclassification. In addition, such approaches, which compare indices of presumed ability potential and actual attainment, preclude early detection of reading disabilities. We propose a skill-based approach based on the growth of requisite precursor abilities underlying successful reading rather than attainment of designated levels of performance. Analysis of individual growth curves yields a quantification of learning that can form the basis for designating children at risk for reading difficulties, and provide an alternative to definitions based on ability potential/achievement discrepancies. To accomplish these objectives, we propose to study the development of precursors of reading and spelling in a broad based sample of kindergarten, first, and second grade children. We propose to use a modified longitudinal time-sequential design with N=900 children studied for one to three years and to assess the utility of using growth rates of reading and spelling precursors and related skills as predictors of growth and attainment in reading and spelling. Three specific aims are proposed addressing (a) reading precursors; (b) predictive utility; and (c) identification. We predict that: 1. Reading Precursors: Kindergarten children will differ in their growth and development of precursor skills, viz. orthographic and phonological awareness, and visual-motor integration. 2. Predictive Utility: The rate of development of the precursors will positively relate to the rate of development and the level of attainment of reading and spelling skill. In turn, individual growth rates in reading and spelling skills will predict performance on standardized tests of reading and spelling, and in-class performance. 3. Identification: The use of growth rates for skills and precursors will (1) allow for earlier identification of children at risk for poor academic outcomes and (2) lead to more stable predictions regarding future academic performance.